<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

    <a href="https://tutorial.javascript.ac.cn/">JavaScript Tutorial</a>

    <script>
        window.addEventListener('beforeunload', function (e) {
            e.preventDefault();
            e.returnValue = '';
            console.log(e.target);
        });
        addEventListener('unload', (event) => {
            console.log('The page is unloaded');
        });

    </script>
</body>

</html>